Rotary electric machine and electric wheelchair mounted with rotary electric machine

ABSTRACT

A rotary electric machine comprises a stator including a plurality of teeth which are wound up by coils and a stator yoke core connecting the respective teeth, and a rotor provided with magnets disposed so as to oppose to the teeth, respectively, with a space therebetween. Each of the teeth (tooth) is formed into T shape by laminating a plurality of magnetic steel plates and has a head portion and a leg portion, the head portion being a wider portion of the T-shape which is opposed to the magnet, the leg portion including a coil wind-up portion which has a substantially constant width and an insert portion which is inserted into the stator yoke core, and the coil wind-up portion is formed with a plurality of fitting portions for fitting and fixing the laminated magnetic steel plates together, the fitting portions being arranged so as to align along a center line of the coil wind-up portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotary electric machine capable ofsuppressing an energy loss due to induction or induced current byimproving teeth of a stator and also relates to an electric wheelchair(or electrically powered wheelchair) mounted with such rotary electricmachine.

2. Related Art

In a known art, as such a rotary electric machine, there has beenprovided an axial gap type rotary electric machine as shown, forexample, in FIGS. 16 to 19.

Referring to FIGS. 16 to 19, the rotary electric machine is providedwith a stator 3 formed with teeth 2 and a rotor provided with aplurality of magnets (permanent magnets), not shown, in which the statorand the rotor are arranged with a gap in a rotation axis direction.

More in detail, the each tooth 2 is composed of a plurality of steelplates 2 a laminated in a radial direction thereof for a countermeasureto core loss, and a plurality of such teeth 2 are arranged and fixedside by side with a predetermined distance in the circumferentialdirection of a disc, i.e., substantially ring-shaped, stator yoke core6. Coils are wound up around these teeth 2 through insulating materialas bobbins, not shown. Further, as shown in FIG. 17, the teeth 2, thestator yoke core 6 and the coils are integrally fixed by means ofmolding resin 7 as shown in FIG. 16 such that surfaces 2 b of the teeth2 opposing to the rotor are exposed.

The steel plates 2 a of the teeth 2 are assembled to the stator yokecore 6 in a separated state and then molded and fixed together by meansof molding resin 7.

However, in such arrangement, it was troublesome to assemble theseparated steel plates 2 a, which involved cost increasing, thus beingdisadvantageous.

Because of such reason, in order to reduce troublesome working or lossin assembling, the respective steel plates 2 a have been preliminarilyfixed by caulking means, for example, such as half pierce member orlike. Such structure is for example disclosed in Japanese PatentLaid-open (KOKAI) Publication HEI 11-318059.

This publication shows salient-pole type core lamination platescorresponding to the steel plates of the teeth mentioned above, the corelamination plates being laminated and fixed by means of a hole formed tothe respective plates. Moreover, at the paragraph [0015] of thispublication, there is a disclosure such that the holes are formed bypunching process, and at the paragraph [0014], the punched-out platesare figured at a portion above the figure of a rolled steel plate in therespective pressing stage in FIG. 2. According to such description, itis apparent that the holes formed to the core lamination plates arethrough holes.

However, in the case where the respective steel plates 2 a are fixed byusing the half pierce member, when the fixing is made only at oneportion, there is a fear of being separated during its assemblingprocess because of no sufficient strength. For this reason, in order toachieve sufficient calking strength, it becomes necessary to calk therespective steel plates 2 a at plural positions.

In addition, although these steel plates 2 a are insulated by insulatingfilms, such insulating films may be broken by the formation of the halfpierce member, which may result in short-circuiting, and the respectivesteel plates 2 a become electrically connected state. Accordingly, ifsuch half pierce members are located at several portions, a closedcircuit will be presented through these half pierce members, and amagnetic flux crosses this closed circuit and then the induction currentpasses, resulting in the cause of energy loss, thus being inconvenientand disadvantageous.

It has been therefore required to accept either one of conditions of (1)cost-up in assembling for achieving high efficiency (reduction ofinduction current loss) without forming the half pierce member or (2)efficiency-down for the reduction of cost.

Further, the holes for fixing the respective core lamination platescorresponding to the steel plates of the teeth (tooth) are formed in theabove prior art publication, but these holes are through holes, whichare not for causing the induction current.

SUMMARY OF THE INVENTION

The present invention was conceived in consideration of the above priorart, and an object of the present invention is to provide a rotaryelectric machine capable of minimally suppressing the induction currentloss even if teeth are fixed through fitting portions and also toprovide an electric wheelchair mounted with such rotary electricmachine.

These and other objects can be achieved according to the presentinvention by providing, in one aspect, a rotary electric machinecomprising:

a stator including a plurality of teeth which are wound up by coils anda stator yoke core connecting the respective teeth; and

a rotor provided with magnets disposed so as to oppose to the teeth,respectively, with a space therebetween,

wherein each of the teeth is formed into T shape by laminating aplurality of magnetic steel plates and has a head portion and a legportion, the head portion being a wider portion of the T-shape which isopposed to the magnet, the leg portion including a coil wind-up portionaround which a coil is wound up and which has a substantially constantwidth and an insert portion which is inserted into the stator yoke core,and the coil wind-up portion is formed with a plurality of fittingportions for fitting and fixing the laminated magnetic steel platestogether, the fitting portions being arranged so as to align along acenter line of the coil wind-up portion.

In a preferred embodiment of this aspect, it may be desired that thefitting portion is formed in an area apart from the head portion and theinsert portion by not less than a ½ length of a width of the coilwind-up portion.

The teeth and the magnets may be arranged so as to oppose to each otherwith a space in a rotation axis direction.

It is desirable that the magnetic steel plates have both side surfaceson which insulating film is formed other than the fitting portion sothat a closed circuit is formed between the magnetic steel platesthrough the fitting portions. The insulating film formed on the sidesurfaces of the magnetic steel plates is broken at the fitting portionwhen the fitting portions are formed and fitted to the steel plates.

The fitting portions may be formed to the respective steel plates so asto have protruded portions and recessed portions such that the protrudedportion of the fitting portion of one magnetic steel plate is fitted andfixed to the recessed portion of the fitting portion of an adjacentmagnetic steel plate when the magnetic steel plates are laminatedtogether.

It may be desired that the fitting portions are formed in parallel withor on the center line of the coil wind-up portion.

It is desirable that the fitting portions are each formed as a halfpierce portion having a half protruded portion and half recessed portionor each formed as a V-shaped calking portion.

According to the rotary electric machine of the present invention of thecharacteristics mentioned above, a plurality of fitting portions formedto the coil wind-up portions, each having substantially the constantwidth, of the teeth are arranged along the center line of this wind-upportion. Therefore, at the time of high flux density in the coil wind-upportion, the magnetic flux flows in the same direction as that of thecenter line thereof, and by arranging the plural fitting portions inalignment with the same direction as that of the center line, thevariation in the magnetic flux flowing the closed circuit formed betweenthe fitting portions can be significantly suppressed, and hence, theloss of energy can be also reduced. In addition, the formation of theplural fitting portions can contribute to the assembling performance ofthe rotary electric machine with improved strength against conveyance,transportation or like.

Moreover, according to the other features of the present invention,since the fitting portions are formed at portions apart from the headportion or insert portion of the tooth by not less than ½ width of thewind-up portion thereof, the disturbance of the magnetic flux at theportions near the head portion, the stator yoke core or yoke insertportion can be significantly suppressed and the loss of energy can bealso suppressed.

The rotary electric machine formed according to the present inventionhas a compact, flat and lightweight structure with the small loss ofenergy can be provided.

Furthermore, each of the fitting portions formed to the magnetic steelplates has protruded and recessed portions, and the protruded portion ofone steel plate is fitted to the recessed portion of the other adjacentsteel plate to thereby easily laminate and fix the respective steelplates together.

In another aspect of the present invention, there is also provided anelectric wheelchair comprising:

a frame structure constituting a vehicle body frame;

a seat disposed on the frame structure;

a pair of driving wheel units including two wheels;

an electric motor mounted to each of the paired driving wheel units; and

an operation member operatively connected to the electric motor foroperating the driving wheel units,

wherein the electric motor comprises a rotary electric machine, whichcomprises a stator including a plurality of teeth which are wound up bycoils and a stator yoke core connecting the respective teeth and a rotorprovided with magnets disposed so as to oppose to the teeth,respectively, with a space therebetween, in which each of the teeth isformed into T shape by laminating a plurality of magnetic steel platesand has a head portion and a leg portion, the head portion being a widerportion of the T-shape which is opposed to the magnet, the leg portionincluding a coil wind-up portion around which a coil is wound up andwhich has a substantially constant width and an insert portion which isinserted into the stator yoke core, and the coil wind-up portion isformed with a plurality of fitting portions for fitting and fixing thelaminated magnetic steel plates together, the fitting portions beingarranged so as to align along a center line of the coil wind-up portion.

According to this aspect, the electric wheelchair mounted with theimproved rotary electric machine having compact structure and highoutput performance can be provided.

The nature and further characteristic features of the present inventionwill be made more clear from the following descriptions made withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a side view of an electric wheelchair mounted with an electricmotor according to a first embodiment of the present invention;

FIG. 2 is a sectional view of the electric motor for the electricwheelchair of the first embodiment;

FIG. 3 is a perspective view of a rotor of the electric motor of FIG. 2;

FIG. 4 is a front view of the rotor of the electric motor of FIG. 2;

FIG. 5 is a perspective view of a stator of the electric motor of theelectric wheelchair of the first embodiment;

FIG. 6 is a back-side view of the stator of FIG. 5;

FIG. 7 is a perspective view of the stator, before molding, of theelectric motor according to the first embodiment;

FIG. 8 is a developed perspective view showing a portion of the statorof the electric motor of the electric wheelchair of the firstembodiment;

FIG. 9 is a front view of the tooth of the stator of the electric motor;

FIG. 10 is a sectional view taken along the line X-X in FIG. 9;

FIG. 11 is an illustration of an arrangement of a stator yoke core andthe teeth according to the first embodiment;

FIGS. 12A and 12B are views showing magnetic fluxes concerning theelectric motor according to the first embodiment, which are different inthe position of the rotor;

FIG. 13 is a front view of the tooth of the electric motor according toa second embodiment of the present invention;

FIG. 14 is a sectional view taken along the line XIV-XIV of FIG. 13;

FIG. 15 is a modification of the second embodiment and shows aperspective view of the stator of the electric motor corresponding toFIG. 5;

FIG. 16 is a perspective view of a stator of a conventional structure;

FIG. 17 is a perspective view showing a stator yoke core and teeth ofthe stator of FIG. 16;

FIG. 18 is a perspective view of the tooth of the conventionalstructure; and

FIG. 19 is a front view of the tooth.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments of the present invention will be describedhereunder with reference to the accompanying drawings.

[First Embodiment]

The first embodiment of the present invention is represented by FIGS. 1to 12.

With reference to FIG. 1, reference numeral 11 denotes an electricwheelchair or electrically powered wheelchair mounted with an electricmotor 12 as a “rotary electric machine” according to the presentinvention, and the electric wheelchair is driven and traveled by thedriving force of the electric motor 12.

The electric wheelchair 11 is provided with a frame 13 as a framework ofa vehicle (electric wheelchair body), a seat 14 on which a user sits anda pair of driving wheel units 15 in which the electric motors 12 aremounted. When an operation unit 17 of the electric wheelchair 11 isoperated, the paired driving wheel units 15 are driven so as to drivedriven wheels 16 by predetermined amount (distance). The driven wheels16 are operated independently, and by the operation of the operationunit 17, the driven wheels 16 are changed in their rotating directionsand driven speed, respectively.

The driving wheel unit 15 is composed, as unit, of the electric motor12, the driving unit, the driven unit 16 and so on, and as shown in FIG.2, the driving wheel unit 15 is fixed to the frame 13 by means of bolt19 and nut 19 a.

The electric motor 12 is of an axial gap type composed of a stator 21and a rotor 22, which are accommodated in a space defined by a case 23and a cover 24. The bolt 19 is planted to the cover 24.

The stator 21 is fastened to the case 23 by means of bolt 51, and on theother hand, the rotor 22 is fitted to a rotor shaft 30, throughserration fitting, provided for the case 23 to be rotatable throughbearings 27, 27 and fixed thereto.

The rotor 22 has, as shown in FIGS. 3 and 4, a disc shaped rotor yoke33, which has a central portion fitted to the rotor shaft 30 through theserration fitting. A plurality of magnets 34, each having a rectangularshape, are arranged and bonded to be fixed to the peripheral edgeportion of the rotor yoke 33 at a predetermined constant interval in thecircumferential direction thereof. These magnets 34 are disposed so asto oppose to the stator 21 with a gap C (FIG. 2) in the rotation axisdirection.

These magnets 34 are arranged so that N and S poles are adjacentlyalternated and bonded and fixed to the rotor yoke 33 in the shape ofcircle.

The rotor yoke 33 is press worked as shown in FIGS. 2 and 3 so as toprovide a central recessed shape 33 a, and in this recessed portion 33a, an electromagnetic brake 36 fixed to the cover 24 is accommodated. Anannular rotary body 36 a and the rotor 22, of which rotations arestopped by the electromagnetic brake 36, are made stationary in therotating direction through a pin 37. Moreover, on the other hand, asensor magnet 38 is bonded and fixed to the opposite side of therecessed portion 33 a, and a pole position sensor (hole IC) 40 opposingto the sensor magnet 38 is fixed to the case 23. The pole positionsensor 40 is electrically connected to a controller 39, and the poleposition of the rotor 22 is detected by the pole position sensor 40.

Further, a sun-gear 30 a is mounted to the rotor shaft 30 so as to bemeshed with a two-staged planetary gear 42 a of a planetary reductiongear 42. The planetary reduction gear 42 reduces the rotation of therotor 22, which is then transmitted to a hub 44, and the rotation of thehub 44 rotates the driving wheel 16.

On the other hand, the stator 21 is provided with a substantially disc(ring) shaped stator yoke core 47, a plurality of teeth 48 arranged inthe circumferential direction of the stator yoke core 47 with apredetermined interval and a coil 50 wound up around each of the teeth(i.e., tooth) 48 through bobbins 49. These stator yoke core 47, theteeth 48 and the coils 50 are integrally molded and fixed together. Atthis time, a plurality of collars 53 are inserted around the stator 21to thereby simultaneously form mount flanges 52 a.

These mount flanges 52 a are fixed to the case 23 by means of bolts 51.

The coil 50 is coupled with each of U, V and W-phases, and one end ofeach coupling coil is electrically connected (neutral point) and theother end thereof is derived out of the mold so as to be connected to adriver.

More in detail, the stator yoke core 47 is formed from a plurality ofsteel plates 54, having the same shape, which are laminated as shown inFIG. 8, and formed with fitting holes 47 a into which teeth 48 areinserted.

The tooth 48 is formed by laminating a plurality of magnetic steelplates 57 so as to provide a T-shape, and is composed of a wider headportion 48 a, which is opposed to the magnet 34 of the T-shaped tooth48, and a leg portion 48 b thereof. The leg portion 48 b includes a coilwind-up portion 48 c having a constant width around which the coil 50 iswound up and an insert portion 48 d to be inserted into the fitting hole47 a of the stator yoke core 47.

The wind-up portion 48 c is formed with a plurality of half pierceportions 57 a (two portions in the illustration) as fitting portions forfixing a plurality of laminated magnetic steel plates 57. Further, thehalf pierce portion 57 a is in the form of half blind hole shape (havingconcave-convex portion), so that this portion is called as “half pierceportion” 57 a herein. The half pierce portions 57 a are arranged in thedirection parallel with the center line O1 of the wind-up portion 48 c,and in the illustration, they are arranged on the center line O1 whichis substantially parallel to the longitudinal direction of T-shapedtooth (or vertical direction in FIG. 9).

These two half pierce portions 57 a is positioned in an area A apartfrom the head portion 48 a and the insert portion 48 d by ½ distance ofthe width W of the wind-up portion 48 c as shown in the hatched portionof FIG. 11.

As also shown in FIG. 10, each of the half pierce portions 57 a of onemagnetic steel plate 57 has a substantially rectangular, in section,protruded portion 57 b which is fitted into a recessed portion 57 c ofthe half pierce portion 57 a of the adjacent one magnetic steel plate57. The magnetic steel plate 57 is coated, at its both side surfaces,with an insulating film 57 d entirely to be insulated. However, the sidesurface portion 57 e of the fitting protruded portion 57 b and the sidesurface portion 57 f of the fitted recessed portion 57 c are not coatedwith the insulating film because of the formation of the half piercedportion 57 a, so that the adjacent magnetic steel plates 57 areelectrically short-circuited as shown with arrows in FIG. 10, thusconstituting a closed circuit.

Furthermore, the insert portion 48 d of the tooth 48 is formed with aresin filling groove 48 f in which a molding resin 52 is filled up so asto prevent the tooth 48 from coming off. The head portion 48 a thereofis also formed with an opposing surface 48 g opposing to the magnet 34of the rotor 22, and a protruded portion 48 h is formed to the opposingsurface 48 g at substantially a central portion in the statorcircumferential direction so as to extend radially. The protrudedportion 48 h has the same height and width in the entire lengthdirection thereof. The opposing side surfaces 48 g except the protrudedportion 48 h are embedded with the molding resin 52 as shown in FIG. 5.

The opposing surface 48 g of the tooth 48 and the magnet 34 of the rotor22 are arranged so as to oppose to each other through a gap C in therotation axis direction.

Further, in FIG. 2, reference numeral 59 denotes a spork of the wheeland 60 denotes a hand rim.

The first embodiment will be operated in the manner mentioned hereunder.

When current passes the coil 50 to be energized so as to drive theelectric motor 12, the magnetic force of the coil 50 and that of themagnet 34 are combined to thereby generate magnetic force between thestator 21 and the rotor 22, thus rotating the rotor 22 and then drivingthe driven wheel 16 through the rotor shaft 30, the hub 44 and so on.

At this time, as shown in FIGS. 12A and 12B, the magnetic flux flowsthrough the rotor yoke 33, the magnet 34, the teeth 48 and the statoryoke core 47, and the magnetic flux flows in parallel with the centerline O1 (see FIG. 11) at the wind-up portion 48 c of the tooth legportion, but the flux flow directions in other portions such as headportion 48 a and the insert portion 48 d are not constant. Accordingly,by forming the plural half pierce portions 57 a along the center line O1to the wind-up portion 48 c at which the magnetic flux flows in parallelwith the center line O1, the closed circuit constituted by the structureof the half pierce portions 57 a is also formed along the center lineO1, whereby the change in the magnetic flux flowing across the closedcircuit can be reduced, and as a result, the induction current passingthe closed circuit is also reduced to thereby suppress the energy loss.

On the contrary, in a case where a pair of half pierce portions 57 a arearranged in a direction inclined with respect to the center line O1 asshown with two-dot-chain line X in FIG. 9, for example, the closedcircuit formed by the short-circuited half pierce portions 57 a and themagnetic flux flowing in parallel with the center line O1 interlinkseach other. Then, according to the change in the magnetic flux, aninduction voltage obtained by differentiating an interlinking flux isgenerated in this closed circuit, which then causes an inductioncurrent.

FIG. 12A shows the magnetic flux flow in an arrangement in which thecenter line O1 of the wind-up portion 48 c and a center line O2 of themagnet 34 are coincident with each other, and FIG. 12B shows themagnetic flux flow in an arrangement in which the center lines O1 and O2are not coincident and slightly shifted from each other. As shown inFIG. 12B, although the flow of the magnetic flux is disturbed at theportion near the head portion 48 a and the insert portion 48 d, byproviding the two half pierce portions 57 a in the hatched area A apartfrom the head portion 48 a and the insert portion 48 d by the distanceof not less than ½ width of the wind-up portion 48 c as shown in FIG.11, the magnetic flux flows along the center line O1 in this area A, sothat the generation of the induction current can be further suppressed,thus reducing the energy loss.

Further, since the tooth 48 shown in FIG. 8 is formed by laminating aplurality of magnetic steel plates 57 of the same kind, working cost andmolding cost can be suppressed minimally, and in addition, thesemagnetic steel plates 57 are caulked and fixed by the half pierceportions 57 a, so that these steel plates can be easily laminated andassembled as the tooth.

Furthermore, the teeth 48 are formed with the resin filling grooves 48 feach having a wide inner space in which the molding resin 52 is filledup, so that the teeth 48 can be firmly fixed to the stator yoke core 47to thereby preventing then from coming off.

Still furthermore, the coming-off prevention structure against theattractive force of the magnet 34 can be also formed by covering, withthe molding resin 52, portions other than the protruded portion 48 h ofthe opposing surface 48 g of the tooth 48.

Further, according to the electric motor 12 of the embodiment of thepresent invention, the energy loss can be suppressed minimally, so thatan electric wheelchair 11 provided with such electric motor 12 can bealso preferably provided.

[Second Embodiment]

FIGS. 13 and 14 represent the second embodiment of the presentinvention.

In this second embodiment, the structure of the fitting portion differsfrom that of the first embodiment.

That is, in the first embodiment, the half pierce portion 57 a hassubstantially the circular shape as a front view, but in this secondembodiment, this portion has a rectangular shape in the direction alongthe center line O1 of the wind-up portion 48 c as shown in FIG. 13, andthe respective magnetic plates 57 are caulked and fixed together byV-shaped caulking portions 57 f each showing V-shape as shown in FIG. 14in cross-section. These two caulking portions 57 f are arranged along oron the center line O1 of the wind-up portion 48 c as like as the halfpierce portions 57 a of the first embodiment.

The structures other than the above are substantially the same as thosein the first embodiment, so that explanation thereof is omitted herein.

It is to be noted that the present invention is not limited to thedescribed embodiment and many other changes and modifications may bemade without departing from the scopes of the appended claims.

For example, in the first and second embodiment of the present inventionmentioned above, the “fixing portion” such as half pierce portions inthe first embodiment or V-shaped caulking portions in the secondembodiment are formed simultaneously in the pressing process of thesteel plates 57, and in the subsequent process, when the plural steelplates are laminated and pressed, the “fitting portions” are fitted andfixed together. However, the present invention is not limited to thedescribed lamination method.

The structure of the fitting portions is also not limited to thedescribed embodiment and many other changes may be made as far as thesteel plates can be laminated and fixed together.

Still furthermore, although in the described embodiments, two halfpierce portions or calking portions are formed, three or more ones maybe formed or a plurality of rows of them may be also formed along thecenter line.

Still furthermore, although in the described embodiments, the portion ofthe tooth 48 other than the protruded portions 48 h of the opposingsurface 48 a of the tooth is covered by the molding resin 52, theseportions may be partially covered by the molding resin as shown in FIG.15.

1. A rotary electric machine comprising: a stator including a pluralityof teeth which are wound up by coils and a stator yoke core connectingthe respective teeth; and a rotor provided with magnets disposed so asto oppose to the teeth, respectively, with a space therebetween, whereineach of the teeth is formed into T shape by laminating a plurality ofmagnetic steel plates and has a head portion and a leg portion, the headportion being a wider portion of the T-shape which is opposed to themagnet, the leg portion including a coil wind-up portion around which acoil is wound up and which has a substantially constant width and aninsert portion which is inserted into the stator yoke core, and the coilwind-up portion is formed with a plurality of fitting portions forfitting and fixing the laminated magnetic steel plates together, thefitting portions being arranged so as to align along a center line ofthe coil wind-up portion.
 2. The rotary electric machine according toclaim 1, wherein the fitting portion is formed in an area apart from thehead portion and the insert portion by not less than a ½ length of awidth of the coil wind-up portion.
 3. The rotary electric machineaccording to claim 1, wherein the teeth and the magnets are arranged soas to oppose to each other with a space in a rotation axis direction. 4.The rotary electric machine according to claim 1, wherein the magneticsteel plates have both side surfaces on which insulating film is formedother than the fitting portions so that a closed circuit is formedbetween the magnetic steel plates through the fitting portions.
 5. Therotary electric machine according to claim 4, wherein the insulatingfilm formed on the side surfaces of the magnetic steel plates is brokenat the fitting portion when the fitting portions are formed and fittedto the steel plates.
 6. The rotary electric machine according to claim1, wherein the fitting portions are formed to the respective steelplates so as to have protruded portions and recessed portions such thatthe protruded portion of the fitting portion of one magnetic steel plateis fitted and fixed to the recessed portion of the fitting portion of anadjacent magnetic steel plate when the magnetic steel plates arelaminated together.
 7. The rotary electric machine according to claim 1,wherein the fitting portions are formed in parallel with the center lineof the coil wind-up portion.
 8. The rotary electric machine according toclaim 1, wherein the fitting portions are formed on the center line ofthe coil wind-up portion.
 9. The rotary electric machine according toclaim 1, wherein the fitting portions are each formed as a half pierceportion having a half protruded portion and half recessed portion. 10.The rotary electric machine according to claim 1, wherein the fittingportions are each formed as a V-shaped calking portion.
 11. An electricwheelchair comprising: a frame structure constituting a vehicle bodyframe; a seat disposed on the frame structure; a pair of driving wheelunits including two wheels; an electric motor mounted to each of thepaired driving wheel units; and an operation member operativelyconnected to the electric motor for operating the driving wheel units,wherein the electric motor comprises a rotary electric machine, whichcomprises a stator including a plurality of teeth which are wound up bycoils and a stator yoke core connecting the respective teeth and a rotorprovided with magnets disposed so as to oppose to the teeth,respectively, with a space therebetween, in which each of the teeth isformed into T shape by laminating a plurality of magnetic steel platesand has a head portion and a leg portion, the head portion being a widerportion of the T-shape which is opposed to the magnet, the leg portionincluding a coil wind-up portion around which a coil is wound up andwhich has a substantially constant width and an insert portion which isinserted into the stator yoke core, and the coil wind-up portion isformed with a plurality of fitting portions for fitting and fixing thelaminated magnetic steel plates together, the fitting portions beingarranged so as to align along a center line of the coil wind-up portion.